The present invention relates to an automatic power control method and apparatus for data processing systems which carries out data processing according to a program stored in a memory.
It is assumed that in view of the rising cost of labor that the automatic operation of data processing systems will increase. In particular, the automation of power ON/OFF control lessens the necessity for operators to go to work early in the morning and to work till late at night, which fact reduces labor costs and improves labor conditions. The automatic power ON/OFF control is therefore regarded as having a principal role in the automatic operation of data processing systems.
Hitherto, the ON/OFF control of the power supply for a data processing system has generally been effected in the following manner. The power supply is automatically turned ON by an automatic power ON/OFF control unit on the basis of the power ON reservation time which has already been set and is automatically turned OFF by the power ON/OFF control unit in response to a power OFF instruction which is given to the unit by a program when a condition which has been specified is satisfied, for example, when a predetermined job stream is ended, or when a predetermined time is reached.
As described above, in the conventional automatic power ON/OFF control method, the relationship between the present time and the power ON reservation time is not taken into consideration at the time when the power supply is turned OFF. For this reason, the conventional method involves the following disadvantages. Namely, in the case where the present time at which the power OFF condition is satisfied is subsequent to the power ON reservation time schedule for the next power ON operation, the power supply of the system is undesirably turned OFF when in fact that, at that time, the power supply should be turned ON by the power ON/OFF control unit. Further, if the data processing system is such that it is repeatedly used in a manner causing the power supply to be turned ON immediately after the power supply has been turned OFF, and since the power ON reservation time is reached immediately after the power OFF operation, the reliability of hardware of the system is adversely affected. Furthermore, even in the case where the power supply is turned OFF because of occurrence of a serious hardware fault which makes it impossible to carry on the system operation, when the power ON reservation time is reached, the power supply of the system is undesirably turned ON again by the automatic power ON/OFF control unit, which fact may make the trouble worse.